biological molecules Flashcards
(88 cards)
1
Q
condensation
A
the removal of a water molecule from the formation of a covalent bond between two biochemical groups
2
Q
hydrolysis
A
the breaking down of large molecules into smaller ones by the addition of a molecule of water
3
Q
Why are inorganic ions important
A
- cellular processes
- includig muscle contraction and nervous coordinations
4
Q
what are inorganic ions also known as and describe the amounts they are needed in
A
- electrolytes
- minute amounts - micronutrients eg zinc
- small amounts - macronutrients
5
Q
What is the role of magnesium ions
A
- consitiuent chlorophyll
- therefore needed for photosynthesis
- therfore when lacking leaves appear yellow - chlorosis
6
Q
What are the roles of iron ions
A
- constitunet of haemoglobin
- involved in transport of oxygen
- a diet deficients in iron can lead to anaemia
7
Q
What is the role of calcium ions
A
- structural component of bones and teeth
- phosphate also required
8
Q
What is the role of phosphate ions
A
- needed for making nucleotides including ATP
- a consititudent part of phospholipids in cell membranes
9
Q
What is an ion
A
- charged atom or molecule that has gained or lost electrons
10
Q
dipolar
A
a polar molecule with a positive and negative charge
11
Q
hydrogen bond
A
weak attractive force between a positivley charged hydrogen atom and a negativley charged oxygen or nitrogen atom
12
Q
Why is water vital to life on earth
A
- makes up between 65%-95% by mass of most organisms
- allows imprtant reactions to take place
- forms a habitat that covers over 70% of the earth’s surface
13
Q
Describe water’s basic structure that enables it’s properties to stem from
A
- dipolar molecule - positivley charged end hydrogen and a negativley charged end oxygen
- no overall charge
- hydrogen bonds easily form between hydrogen on one molecule and oxygen on another
- although individulally there weak collectivley they make it difficult to seperate molecules from each other
14
Q
Why is water a good solvent and how is this useful for life on earth
A
- it is involved in many biochemical reactions
- hydrolysis and condenasation
- allows polar molecules eg glucose and ions to dissolve
- acts as a transport medium - eg blood
15
Q
Why does water have a high specific heat capacity and how is this useful for life on earth
A
- a large amount of heat energy is needed to increase the temerature of a body of water - due to large numbers of hydrogen bonds that need to be broken
- large fluctuations in temperature are prevented
- aquatic environments are therfore relativley thermally stable
16
Q
Why does water have a high latent heat of vaporisation and how is this useful for life on earth
A
- large amounts of heat energy are needed to vaporise water
- often used as a cooling mechanism eg sweating in mammals
17
Q
Why is water a good metabolite and how is this useful for life on earth
A
- it is involved in many biochemical reactions
- hydrolysis and condensation
- reactant in photosynthesis
18
Q
Why does water have cohesion and how is this useful for life on earth
A
- water molecules attract each other and form hydrogen bonds between themselves
- allows water to be drawn up xylem vessles of trees
- created surface tension allowing insects such as pond skaters to be supported
- also provides support for other aquatic organisms eg jellyfish
19
Q
Why does water have a high density and how is this useful for life on earth
A
- water has a maximum density at 4 degrees celcius
- as a result ice floats act as an insulator preventing the water benath from freezing complelteu
- preotecting the aquatic habitat
20
Q
Why is water transparent and how is this useful for life on earth
A
- allows light to pass through enabling aquatic plants to photosynthesise
21
Q
What are carbohydrates
A
small organic molecules containing carbon, oxygen and hydrogen
22
Q
What are the role of carbohydrates
A
- building blocks for more complex molecules eg ribose forms a consituent molecule of RNA
- sources of energy eg glucose
- energy storage molecules eg glycogen and starch
- structural support eg cellulose and chitin
23
Q
isomer
A
- molecules with the same chemical formular with a different arrangement of atoms
24
Q
What are the properties of monosaccharides
A
- sweet tasting
- soluble in water
25
what are monosaccharides
* contains single sugars all contain carbon , hydrogen and oxygen in the following proportions (CH2O)n where n is the number between 3 and 6
26
What are triose sugars and there function
* 3 C atoms
* respiratory pathways
27
What are pentose sugars and there function
* 5C atoms
* sugars ribose and deoxyribose important consituent of ribonucleic acids and deoxyribonucleic acids (DNA)
28
What is glucose
* hexose sugar 6 C atoms
* starting material for respiration and building block of glycogen and other polypeptides
29
What are the three hexose sugars
* glucose
* fructose
* galactosse
30
what are the two isomers of glucose and how do they differ
* alpha glucose and beta glucose
* hydroxyl group on alpha glucose in the down position onf Carbon 1 and beta glucose has the hydroxyl group in the up position
31
What are dissacharides
* they are formed by joining two monosaccharides together involving the loss of a molecule of water and formation of a glycosidif bond via a condensation reaction
32
Describe the breakdown of disaccharides
* involves the chemical addition of water known as hydrolysis
33
What is maltose made up of and its function
* glucose + glucose
* germinating seeds
34
What is sucrose made up of and its function
* glucose + fructose
* transport in phloem in flowering plants
35
What is lactose made up of and its function
* glucose + galactose
* mammalian milk
36
How do you test for the prescence of reducing sugars
* a reducing sugar donates an electron to reduce blue cooper (II) ions present in copper sulphate to red copper (I) oxide
* add an equal volume of benedicts reagent (blue) to the solution being tested and strongly heat in a boiling water bath
* if a reducing sugar such as glucose is present the solution with gradually turn form blue through green l yellow, organge and finall a brick red preciptitate forms
37
What are reducing sugars
* monosaccharides and some disaccharides
* maltose and lactose
38
Describe the test for non reducing sugars
* cannot reduce copper (II) ions in copper sulphate
* heat with hydrochloric acid then neutralise by adding alkali slowly until fizzing stops
* add benedicts reagent and stronglu heat
* solution now turns from blue to red then a non reducing sugar is present
39
What are polysaccharides
* when many monosaccharides combine together to form the polymer polysacchairdes
40
What are the role of polysaccharides
* form a number of structural molecules
* good energy stroage molecule
41
Why are polysaccharides good storage molecules
* unable to diffuse out of the cell
* compact in sahpe so much glucose can be stored in a cell
* insoluble in water so they do not alter the water potential and therefore have no osmotic effect
* easily hydrolysied into their constituent monosaccharides whcih can be used in respiration with the exception of cellulose whcih is difficult to digest due to its fibrous structure
42
What is the role of starch
* main energy store in plants
* found in starch graines seen in most plant cells and chloroplasts
* more common in seeds
* sugars made in phototsynthesis stored as starch unless they are required immediatley for respiration
43
What is starch made up of
* alpha glucose molecules bonded together and consists of two polymers amylose and amylopectin
* amylose is linear, unbranches with glycosididc bonds forming between the first carbon atom on one molecule and the fourth carbon atom on the next molecule referred to as 1-4 glycosidic bonds
* repeated forming a straight chain which coils into a single helix
* amylopectin is branched molecule fits inside amulose
* contains 1-4 glycosidic bonds and 1-6 glycosidic bonds
* when a glycosidic bonds forms between the first carbon on the glucose molecule and sixth carbon on another this greates a side branch
* 1-4 glycosidic bonds then continue on from the start off the branch
* due to its branched structure there are more exposed ends that can be hydrolysed which results in a more rapid release of glucose
44
polymer
a large molecule made up of many repeating units (monomers) bonded together
45
What is the test for starch and a disadvantage of this
* iodine solution - iodine dissolved in an aqueous solution of potassium iodide reacts with any starch present in sample
* colour change from orange brown to blue black
* depth of resulting blue black colour seen may give an indication of concentration however unrelaiable as temperature increases so does colour intensity
46
What is glyogen made up of and its role
* main storage product in animals
* similar to amylopectin however more branched
47
What is cellulose
* structural polysaccharide
* most abundant molecule on earth due to its prescence in plant cell walls
48
What is cellulose made up of
* consists of many beta glucose units bonded together with adjacent glucose molecules rotated by 180 degrees forming lond straight parallel chains cross linked to each other via hydrogen bonds
* become tightly cross linked to form bundles called microfibrils which in tunes are arranged in bundles called fibres
49
what is a disadvantage of cellulose
* despite their strength the gapes between cellulose fibes in plant cell walls make them freely permable allowing water and soluted to penetrate through to the cell membrane
50
What is chitin and advantages of it
* structural polysaccharide
* found in exoskeleton of arthropods - insects
* and cells walls of fungi
* due to strength lightness and water proof properties
51
What is chitin made up of
* similar to cellulose long parallel chains of beta glucose molecules ( with added acteylamine group) coss linked to each other by hydrogen bonds forming microfibrils due to adjacent glucose molecules which are rotated by 180 degrees in similar way to those found in cellulose
* N- acetylglucosamine group
52
What are lipids
* non polar compounds insoluble inw ater
* contain carbon , hydrogen (more than carbohydrates) and oxygen (less than carbohydrates)
53
What are triglycerides made up of and what reaction and bond is formed
* formed by the combination of one glycerol molecule and three molecules of fatty acids via a condensation reaction whereby three molecules of water are removed and an esterbond is formed between glycerol and fatty acid
54
where do the differences between properties of fats and oils come from
* if the hydrocarbon chains has no carbon - carbon double bonds then the fatty acid is saturated - carbon atoms are linked to the maximum possible number of hydrogen atoms)
* therefore these fats are semi solid at room temperature and useful in storage of fats in mammals
* plant lipids are unsaturated and occur as oils
55
Why is a high intake of fat bad
* saturated fats is a factor of heart disease
* animal lipids are often saturated
56
What is monounsaturated
* one carbon- carbon double bond is present
57
what is polyunsaturated
* prescence of many carbon-carbon double bonds
58
What happens to the chainr where carbon-carbon double bonds are present
straight chain fatty acid may kink
59
What are waxes and there role
* type of lipid that melt at temperatures above 45 degrees celcius
* waterproofing role in both animals and plants eg in leaf cuticle
60
What is the role of lipids
* structure of plasma membranes
* major component of myelin sheath that surrounds neurones - increased speed nerve impusles propagated
61
How do lipids act as an energy reserve
* make an excellent energy reserve in both plants and animals
* contain more carbon-hydrogen bonds than carbohydrates
* one gram of fat when oxidised yields approximatley twice as much energy as the same mass of carbohydrates
62
How do lipids help with thermal insulation
* when stored under the skin
* acts as an insulator against heat loss
63
How do lipids help with protection
* fat is often stored around delicate internal organs such as kidneys
* providing protection against physical damage
64
How do lipids help with metabolic water
* triglycerides produce a lot of metabolic water when oxidised
* important in desert animals which survive on metabolic water from respiration of its fat intake
65
How do lipids help with waterproofing
* fats are insolule in water and are important in land organisms such as insects where the waxy cuticle cuts down water loss
* water loss is then only usually possible via the stomata through processess known as transpiration
66
hydrophobic
water hating
cannot interact with water due to the lack of charge on the molecule
67
hydrophillic
water loving
interact with water due to the prescence of charge on the molecule
68
What are phospholipids
* are a special type of a lipid
* where one fatty acid tail is replaced by a phosphate group
* one end is soluble in water and other is not
* fatty acid part is non polar and insolble in water - hydrophobic
* glycerol and phosphate group are polar and dissolve in water -hydrophillic
69
What are phospholipids important for
* formation and functioning of plasma membranes in cells
70
What does a phospholipid compose of
* hydrophillic head containing phosphate group and glycerol
* two hydrophobic fatty acid tails
71
What is the test for fats and oils
* in lipid emulsion test a sample is mixed with ethanol to dissolve any liquid present (lipids are soluble in organic solvents such as ethanol)
* then the sample is shaken with an equal volume of water
* this causes the dissolved lipids to fall out of solution as they are insoluble in water giving the sample a cloudy white emulsion appearance
72
what is the implication of saturated fats on human health
* athersclerosis is the buildup of fatty deposits or plaques called atheromas within artery walls as a result of low density lipoproteins (LDL) from a diet high is saturated fats
* this leads to a narrowing of the arteries
* as the arteries narrow they lose their elasticity and begin to restrict blood flow which limits oxygen delivery to the heart whcih can result in angina
* eventually a heart attack
* atheromas can cause endothelial lining to rupture which causes a clot to form (thrombosis) which can also cause strokes
73
How are high densitry lipoproteins formed and what do they do
* higher proportion of unsaturated fats combined with excercise result body manufacturing high density lipoproteins
* HDL which carry harmful fats to the liver for disposal
74
What does a higher ratio of HDL:LDL in a patients blood do
lower the risk of cardiovascular disease
75
What do proteins contain
* carbon
* hydrogen
* oxygen
* nitrogen
* sometimes sulphur
76
What are proteins made up of
* large components built up of sub units called amino acids
77
How is the protein function determined
* 20 different amino acids used to make up proteins and order of these amino acids that determines the proteins structure and hence its function
78
What is an amino acid made up of
* amino group
* r group
* carboxyl group
79
How is a peptide bond formed
* a condensation reaction occurs between amino group of one amino acid and the carboxyl group of another eliminating water
* the bond is called a peptidee bond and resulting compound is a dipeptide
80
What are polypeptides
proteins are very large molecules and consist of long chains of many amino acid joined together
81
What is the primary structure of a protein
* order of amino acids in a polypeptide chain
* determined by DNA sequence on one strand of the DNA molecule
82
What is the secondary structure of a protein
* involves folding of the primary structure into a 3D shape which is held together by hydrogen bonds between =O on the -COOH group and the H on the NH2 groups
* creates a alpha helix and beta pleated sheet
83
What is the tertiary structure of a protein
* forms from folding of the alpha helix into a more compact shape
* maintained by disulphide, ionic, hydrogen bonds and hydrophobic interactions
* gives globular proteins ef enzymes their shape
84
What is the quantenary structure of a protein
* combination of two or more polypeptide chains in tertiary form combined
* often associated with non protein groups and sometimes form large complex molecules eg haemoglobin
85
What are fibrous proteins, give examples and properties
* perform structural functions
* consist of polypeptides in parallel chains or sheets with numerous cross linkages to form long fibres
* keratin - hair
* insoluble in water strong and tough
* collagen provides tough properties needed in ttendons
* single fibre consists of three polypeptide chains twisted around each other like a rope
* these chains are linked by cross bridges making a very stable molecule
86
What are globular proteins, give examples and properties
* perform a variety of different function
* enzymes, antibodies, plasma proteins and some are hormones eg insulin
* proteins are compact and folded as spherical molecules
* soluble in water
* each protein has a unique and specific shape
87
What does haemoglobin consist of
* haemoglobin consists of four folded polypeptide chains at the centre of each is an iron containing group called haem
88
What is the test for protein
* add a few drops of biuret reagent to your sample
* prescence of a protein will change from blue to purple
